The present invention relates to stereoscopic image presentation in general, and in particular to an autostereoscopic image presentation system which does not require the viewer to wear special eye-glasses.
With the advent of digital television and the widespread use of cable and satellite transmission, monoscopic television technology is approaching a very high state of development. High Definition Television, although not widely available in 1997, has significantly improved television picture quality. Nonetheless, the ultimate realism obtainable by stereoscopic viewing is presently possible only with anaglyphic systems, which require special glasses to separate the left- and right-hand views of a stereoscopic program.
Lack of acceptance of anaglyphic 3-D TV by the general public has led to significant efforts to develop autostereoscopic television systems. For example, U.S. Pat. No. 5,614,941 issued to Hines discloses an autostereoscopic television system employing multiple (generally more than two) different views of the subject, which are processed to produce a 3-D presentation. U.S. Pat. No. 5,349,379 issued to Eichenlaub makes use of head position sensors in processing stereoscopic video images to enable one or more observers to view 3-D displays. in U.S. Pat. No. 4,829,365, Eichenlaub describes a flat liquid crystal display employing equally spaced vertical light sources, disposed behind a liquid crystal display. The display contains left-eye and right-eye information in alternating segments within each horizontal display lines. The vertical light source elements illuminate each left-eye and right-eye information segment to produce autostereoscopic viewing.
Holographic television concepts are under development at the Massachusetts Institute of Technology (MIT) by Benton, and others. The results to date are very computation intensive and result in displays about 4".times.4".times.4" in size or smaller. U.S. Pat. No. 5,521,724 issued to Shires discloses an automultiscopic 3-D system based on HOE's (Holographic Optical Elements).
Known systems based on the parallax barrier concept, however, suffer several shortcomings. First, over half of the light from the monitor screen is blocked. Second, these symptoms impose very severe limitations of head position for stereoscopic viewing. Third, problems exist due to diffraction effects, which often lead to highly objectional diffraction bands.